Watch the doughnut-shaped cloud of ionized gas that Io's volcanoes feed into Jupiter's magnetic field, isolate its three real radial layers, and see its documented bright sector lap Io's own orbit.
Drag to orbit and scroll or pinch to zoom on the scene above. Sizes and distances are compressed for readability - the table below has the real figures.
For related explorers, see the Jupiter Magnetosphere 3D Explorer (the broader magnetic field this torus is trapped inside) or the Io Volcanoes 3D Explorer (the volcanic source feeding the torus).
Io Plasma Torus 3D Explorer
This browser explorer shows the doughnut-shaped ring of ionized gas that circles Jupiter along Io's orbit, isolates its three real radial layers, and reveals a documented bright sector that laps Io's own orbit as it rotates with Jupiter's magnetic field.
Io is the innermost of Jupiter's four large Galilean moons, and it is the most volcanically active body known in the solar system. Its volcanoes vent about 1 tonne of neutral gas - mostly sulfur and oxygen compounds - into space every second. Jupiter's fast-rotating magnetic field ionizes that gas and drags it around the planet, building up a persistent doughnut-shaped cloud of plasma centered on Io's orbit at 5.9 Jupiter radii (RJ). Three radial regions make up the structure, first mapped in detail by Voyager 1 and refined by the Cassini and Juno missions: a cold inner disk under about 5.5 RJ (electron temperature under 1 eV), a dense warm ribbon from about 5.5 to 7.6 RJ that contains Io's own orbit (electron temperature 5-6 eV, with Juno measuring peak electron density near 3,000 per cubic centimeter), and an extended hot outer torus beyond about 7.6 RJ where electron temperature climbs past 100 eV.
The torus is not evenly bright all the way around. Cassini observations found a denser, brighter sector that rotates with Jupiter's magnetic field every 10.07 hours - about 1.5 percent longer than Jupiter's own 9.925-hour System III rotation period. Io itself orbits far slower, once every 42.5 hours (1.769 Earth days), so that bright sector sweeps past Io roughly four times during each of Io's orbits. Toggle the bulge button in the scene to watch that lapping happen. Cassini's UVIS instrument also measured the whole torus radiating about 1.7 terawatts of extreme-ultraviolet light, a figure that varies by up to 25 percent as the torus's density and composition shift over time.
- A layer button cycles through the cold disk, warm ribbon, and extended hot torus, isolating each one on screen
- A bulge button shows or hides the real co-rotating bright sector as it laps Io's slower orbit
- A facts panel updates with the published density, temperature, and radiated-power figures for whichever layer is selected
- Io and the torus keep their own real relative rotation rates, so the four-to-one lapping ratio you see is genuine, not staged
- Drag to orbit, scroll or pinch to zoom
- Runs fully in the browser with the vendored three.js engine - no account, no upload
| Property | Value | Source |
|---|---|---|
| Io's orbital distance | 5.9 Jupiter radii | Standard planetary fact sheets |
| Io's orbital period | 42.5 hours (1.769 Earth days) | Standard planetary fact sheets |
| Torus co-rotation (bright-sector) period | 10.07 hours | Cassini observations |
| Jupiter System III rotation period | 9.925 hours | Standard planetary fact sheets |
| Io's neutral-gas loss rate | about 1 tonne per second | Voyager/Cassini/Juno torus studies |
| Cold disk boundary | under 5.5 Jupiter radii, electron temp under 1 eV | Voyager 1 |
| Warm ribbon range + peak density | 5.5-7.6 Jupiter radii, about 3,000 electrons/cm3 peak | Juno (2016-2022) |
| Extended torus electron temperature | about 30 eV, climbing past 100 eV beyond 12 RJ | Voyager 1 / Cassini UVIS |
| Total radiated power (EUV, 580-1181 A) | about 1.7 terawatts, +/- 25% | Cassini UVIS |
The particle counts, colors, and the bulge's exact shape in the scene are an illustrative teaching device, not a calibrated emission-intensity map or a plasma-transport simulation. The three layer boundaries, the two rotation periods, the density peak, and the radiated-power figure are the real published values summarized in the table above.
The Io plasma torus is a specific named structure sitting inside Jupiter's much larger magnetosphere - the trapped plasma inflates that whole magnetic environment to more than twice the size a simple dipole field would predict. For the overall field geometry the torus sits inside, open the Jupiter Magnetosphere 3D Explorer. For the volcanic activity that supplies the torus's material in the first place, open the Io Volcanoes 3D Explorer.
Everything renders on your device with WebGL. The 3D engine loads once (about 0.7 MB) and is cached.
Frequently Asked Questions
What is the Io plasma torus?
A doughnut-shaped ring of ionized sulfur and oxygen that circles Jupiter along Io's orbit, fed by about 1 tonne of neutral volcanic gas that Io vents into space every second and ionized by Jupiter's magnetic field.
How far from Jupiter is the torus?
It is centered on Io's orbit at 5.9 Jupiter radii, but it spans three regions: a cold disk under about 5.5 Jupiter radii, a warm ribbon from about 5.5 to 7.6 Jupiter radii, and an extended hot torus beyond that.
Why does the bright sector move faster than Io?
The bright sector rotates with Jupiter's magnetic field every 10.07 hours, close to Jupiter's own 9.925-hour rotation period. Io orbits far slower, once every 42.5 hours, so the bright sector laps Io roughly four times per Io orbit.
How dense and hot is the torus?
Juno measured a peak electron density near 3,000 per cubic centimeter in the warm ribbon. Electron temperature ranges from under 1 eV in the cold disk to 5-6 eV in the warm ribbon and past 100 eV in the extended torus beyond 12 Jupiter radii.
How much energy does the torus radiate?
Cassini's UVIS instrument measured the whole torus radiating about 1.7 terawatts of extreme-ultraviolet light, varying by up to 25 percent over time.
Is the 3D scene a real plasma-physics simulation?
No. It is an educational approximation. The point counts, colors, and the bulge's exact shape are an illustrative teaching device, not a calibrated emission-intensity map or an ion-transport simulation. The layer boundaries, rotation periods, density peak, and radiated-power figure shown in the facts panel are the real published values.
Can I isolate one layer of the torus?
Yes. The layer button in the scene cycles through all three layers, the cold disk, the warm ribbon, and the extended hot torus, showing only one at a time.
How is this different from the Galilean Moons explorer?
The Galilean Moons 3D Explorer shows the orbits and real properties of Jupiter's four large moons together. This page instead focuses on one specific consequence of Io's volcanism: the plasma torus it feeds into Jupiter's magnetosphere.
Does this page need an account or upload?
No. It runs entirely in your browser using the vendored three.js engine. There is no account, no upload, and no server processing.